Non-contact charging system

Abstract

Power transmission to a power reception unit that is performed by a power transmission unit and, in turn, non-contact charging of a battery mounted on a vehicle are suspended on the condition that the existence of a foreign object is detected around the power transmission unit. A designated period that is a suspension period of power transmission performed by the power transmission unit is set to vary in accordance with the type of a foreign object, that is, in the present embodiment, depending on whether a foreign object is a metal piece or an object containing metal (first foreign object) or a living body (second foreign object).

What is claimed is: 
     
       1. A non-contact charging system comprising:
 a power transmission unit that transmits power in a non-contact manner to a power reception unit mounted on a vehicle in order to charge a battery mounted on the vehicle; 
 a charging control device that controls an amount of power transmitted by the power transmission unit; and 
 a foreign-object detector that detects an existence of a foreign object existing around the power transmission unit and a type of the foreign object, 
 wherein, the charging control device:
 on a condition that the foreign-object detector detects the existence and the type of the foreign object when the power transmission unit transmits power to the power reception unit, suspends power transmission performed by the power transmission unit for a designated period that varies in accordance with the type of the foreign object, 
 when it is determined that the designated period has elapsed after the power transmission is suspended, changes an index value which indicates the number of trial of power charging, and sets a new designated period according to the type of the foreign object in response to the foreign-object detector detecting the existence and the type of a foreign object, and 
 determines whether the index value has reached a predesignated value, and when it is determined that the index value has reached the predesignated value, stops a control processing for charging the battery of the vehicle. 
 
 
     
     
       2. The non-contact charging system according to  claim 1 ,
 wherein the charging control device causes the power transmission unit to resume power transmission on a condition that the existence of the foreign object is not detected by the foreign-object detector when the designated period has elapsed after the power transmission is suspended. 
 
     
     
       3. The non-contact charging system according to  claim 1 ,
 wherein the charging control device issues a notification prompting removal of the foreign object to a user of the vehicle via an external terminal when power transmission performed by the power transmission unit is suspended for the new designated period. 
 
     
     
       4. The non-contact charging system according to  claim 1 ,
 wherein the foreign-object detector includes 
 a metal detector that detects an existence of an object containing metal as the foreign object existing above the power transmission unit and 
 a living-body detector that detects an existence of a living body as the foreign object existing around the power transmission unit, and 
 wherein the charging control device sets the designated period in accordance with an output signal from the metal detector and an output signal from the living-body detector. 
 
     
     
       5. The non-contact charging system according to  claim 4 ,
 wherein the metal detector includes a coil array that is embedded in a sheet-shaped member included in the power transmission unit, and 
 wherein the living-body detector includes a plurality of ultrasonic sensors that are arranged on a peripheral edge portion of the sheet-shaped member in such a manner as to have different directivities, respectively. 
 
     
     
       6. The non-contact charging system according to  claim 1 ,
 wherein, when the designated period has elapsed after the power transmission is suspended, the foreign-object detector performs detection of the existence and the type of the foreign object, and 
 when the existence of the foreign object is detected, the charging control device suspends power transmission performed by the power transmission unit for the new designated period according to the type of the foreign object. 
 
     
     
       7. The non-contact charging system according to  claim 3 ,
 wherein the charging control device does note issue the notification prompting removal of the foreign object to the user of the vehicle via the external terminal until power transmission performed by the power transmission unit is suspended for the new designated period. 
 
     
     
       8. The non-contact charging system according to  claim 5 ,
 wherein the metal detector detects size of the object, and 
 the living-body detector detects whether a living body moves toward or away from the power transmission unit. 
 
     
     
       9. A non-contact charging method of a non-contact charging system which comprises a power transmission unit that transmits power in a non-contact manner to a power reception unit mounted on a vehicle in order to charge a battery mounted on the vehicle,
 the method comprising the steps of: 
 detecting, by a foreign-object detector, an existence of a foreign object existing around the power transmission unit and a type of the foreign object, 
 wherein 
 on a condition that the existence and the type of the foreign object are detected when the power transmission unit transmits power to the power reception unit, suspending, by a computer, power transmission performed by the power transmission unit for a designated period that varies in accordance with the type of the foreign object, 
 when it is determined that the designated period has elapsed after the power transmission is suspended, changing an index value which indicates the number of trial of power charging, and setting a new designated period according to the type of the foreign object in response to the foreign-object detector detecting the existence and the type of a foreign object, and 
 determining whether the index value has reached a predesignated value, and when it is determined that the index value has reached the predesignated value, stopping a control processing for charging the battery of the vehicle.